Ferulic acid is a very abundant compound in nature, since it is a component of the cell wall of several plant species such as rice, corn, sugar beet and others. However it is not found in its free form, rather it forms glycosidic bonds with the carbohydrate chains in the cell wall, so, for its liberation several hydrolytic methods are used, be it enzymatic or alkaline. For example, in the patent document U.S. Pat. No. 6,143,543 an enzymatic method for the obtention of free ferulic acid is described.
The patent document U.S. Pat. No. 5,288,902 discloses on its example 1, lines 50 to 60, that raw ferulic acid was dissolved in hot water at 90 to 100° C., followed by a cooling, for a re-crystallization, with the purpose of obtaining pure trans-ferulic acid. It is also mentioned that the purity of said ferulic acid is 99.9%. However, one of the inconveniences that this procedure presents is that depending on the origin of the ferulic acid (rice and its derivatives, corn, wheat and other natural sources) other contaminants are found with it, which are also soluble in water like polysaccharides, hemicelluloses, lignins, and by being dissolved in water, they re-crystallize along ferulic acid, and high purity levels are not reached.
Meanwhile, patent application WO2004/110975 discloses a process for the recovery and purification of ferulic acid in its free form using water resulting from corn cooking, known as nejayote, originated from the nixtamal industry. However, according to the purification, it only describes that raw feluric acid can be purified by re-crystallization, gradually decreasing the polarity of a concentrated solution of it in ethyl acetate by the addition of organic solvents of low polarity like methyl chloride and hexane, or by decreasing the pH value of an aqueous alkaline solution.
The patent document CN1621402 refers to the preparation of ferulic acid and the purification process from Chinese medicinal material. The technological process includes the next steps: grind Chinese Ligusticum, angelica or Chuanxiong rhizome, into fine powder; perform a reflux extraction with ethyl ether and solvent methanol, at a pH value of 3-5, to obtain a liquid extract and the recovery of the solvent; wash with dissolvent ethanol and water; filter to obtain a filtrate and recovery of the solvent to obtain a concentrated solution; and dry and freeze in vacuum to obtain the product pure ferulic acid. The obtained product has a purity above 90% and the yield is higher than 65%. The problem with this method is the use of toxic organic solvents, like methanol and ethyl ether, which are not permitted in the food industry, and that remaining may be left in the final product.
The document CN101811958 states a process for the isolation and extraction of natural ferulic acid, with contents higher than 98%, from the residues of processing rice bran oil. The procedure includes the following stages: wash with alcohol; saponify and filter; acidify and filter; dissolve with alcohol and filter; refine with an ionic exchange resin; discolor; concentrate; pump and filter; and drying in vacuum to obtain a white dust with contents of natural ferulic acid higher than 98%. But the inconveniences are: the use of anionic exchange reins, strongly alkaline for purification, in which a loss of product of between 20 and 50% is observed due to the chemical selectivity of them for ferulic acid, which causes retention of the product and cannot be recovered, hence affecting the economics of the process.
Therefore, it is not demonstrated in the state of the technique an efficient methodology for the purification of ferulic acid and/or salts thereof. Reason for which a method to purify ferulic acid and/or salts thereof was developed, which is described next.